Add if not exists support to database ddl in parsing

go/vt/sqlparser/ast.go

@@ -177,11 +177,12 @@ type (
 
 	// DBDDL represents a CREATE, DROP, or ALTER database statement.
 	DBDDL struct {
-		Action   string
-		DBName   string
-		IfExists bool
-		Collate  string
-		Charset  string
+		Action      string
+		DBName      string
+		IfExists    bool
+		IfNotExists bool
+		Collate     string
+		Charset     string
 	}
 
 	// DDL represents a CREATE, ALTER, DROP, RENAME, TRUNCATE or ANALYZE statement.
@@ -359,16 +360,16 @@ type ColumnType struct {
 	Type string
 
 	// Generic field options.
-	NotNull       BoolVal
-	Autoincrement BoolVal
+	NotNull       bool
+	Autoincrement bool
 	Default       Expr
 	OnUpdate      Expr
 	Comment       *Literal
 
 	// Numeric field options
 	Length   *Literal
-	Unsigned BoolVal
-	Zerofill BoolVal
+	Unsigned bool
+	Zerofill bool
 	Scale    *Literal
 
 	// Text field options
@@ -991,7 +992,13 @@ func (node *SetTransaction) Format(buf *TrackedBuffer) {
 // Format formats the node.
 func (node *DBDDL) Format(buf *TrackedBuffer) {
 	switch node.Action {
-	case CreateStr, AlterStr:
+	case CreateStr:
+		notExists := ""
+		if node.IfNotExists {
+			notExists = " if not exists"
+		}
+		buf.WriteString(fmt.Sprintf("%s database%s %v", node.Action, notExists, node.DBName))
+	case AlterStr:
 		buf.WriteString(fmt.Sprintf("%s database %s", node.Action, node.DBName))
 	case DropStr:
 		exists := ""

go/vt/sqlparser/parse_test.go

@@ -1610,16 +1610,17 @@ var (
 		input:  "create schema test_db",
 		output: "create database test_db",
 	}, {
-		input:  "create database if not exists test_db",
-		output: "create database test_db",
+		input: "create database if not exists test_db",
+	}, {
+		input:  "create schema if not exists test_db",
+		output: "create database if not exists test_db",
 	}, {
 		input: "drop database test_db",
 	}, {
 		input:  "drop schema test_db",
 		output: "drop database test_db",
 	}, {
-		input:  "drop database if exists test_db",
-		output: "drop database test_db",
+		input: "drop database if exists test_db",
 	}, {
 		input:  "delete a.*, b.* from tbl_a a, tbl_b b where a.id = b.id and b.name = 'test'",
 		output: "delete a, b from tbl_a as a, tbl_b as b where a.id = b.id and b.name = 'test'",